Rituximab+Standard CHOP vs Rituximab+Bi-weekly CHOP for Untreated Stage III/IV Low-grade B-cell Lymphoma (JCOG0203)

Inclusion Criteria: 1. Histological confirmed, low-grade B-cell lymphoma except mantle cell lymphoma and histologic transformation to DLBCL 2. CD20-positive 3. Ann Arbor CS III or IV 4. Lymphoma cell count in PB≦10,000/mm3 5. 20\<=age\<=69 6. ECOG PS 0-2 7. Bidimensionally measurable disease \>1.5cm in a single dimension by CT scans 8. No prior chemotherapy, radiotherapy, interferon-alfa, or antibody therapy 9. Normal BM, hepatic, renal, cardiac, and pulmonary function 10. Written informed consent Exclusion Criteria: 1. CNS involvement 2. Glaucoma 3. DM treated by insulin 4. Uncontrollable HT 5. AP, AMI 6. Positive HBs antigen 7. seropositive to HCV 8. seropositive to HIV 9. Interstitial pneumonitis, pulmonary fibrosis, or emphysema 10. Severe infection 11. Liver cirrhosis 12. Double cancer 13. Pregnant or lactating 14. Patients who desire auto PBST after CR 15. Patients treated with major tranquilizer or antidepressant